Draft controlling apparatus for furnace flues



Feb. 6, 1934. w PRICE 1,945,955

DRAFT CONTROLLING APPARATUS FOR FURNACE FLUE S Filed 001;. 25, 1930 v figrA'r'roRN I lk Patented Feb. 6, 1934 UNITED STATES DRAFT CONTROLLING APPARATUS FOR FURNACE FLUES Thornton W. Price,

Application October 25,

9 Claims.

This invention relates to a draft controlling apparatus for furnace fiues, and an object of the invention is to provide an apparatus operable to maintain uniform draft conditions within the furnace at all times.

A further object is to provide means for improving the operation and efficiency of a furnace equipped with forced draft and air supplying mechanism, and particularly to provide means so w co-related with the forced draft and air supplying mechanism of the furnace as to automatically at all times, and irrespective of weather conditions, provide just the required amount of discharge for smoke and spent gases from the fire m box without at any period objectionably disturbing the predetermined balance of air conditions existing above, through and below the grate.

A further object is to so design the device that it will provide a wide open flue for the easy and complete discharge of'gases from the furnace to the chimney and will present a high degree of eificiency in preventing escape of such gases into the cellar under abnormal circumstances.

A more detailed object is to provide a draft regulating device, including a lateral air supply extension or pipe disposed and shaped with respect to the main flue to provide a suitable measure of resistance to the passage of air along said extension, and carrying an adjustable balanced valve for further controlling the movement of air within said extension.

A still further detailed object is to provide an improved balanced valve structure for draft regulation.

A further object is to provide an emergency re,- lief for pressure within the flue.

Other objects and aims of the invention, more or less specific than those referred to above, will be in part obvious and in part pointed out in the 49 course of the following description of the elements, combinations, arrangements of parts and applications of principles constituting the invention; and the scope of protection contemplated will be indicated in the appended claims.

In the accompanying drawing which is to be taken as a part of this specification, and in which I have shown merely a preferred form of embodiment of the invention:-

Fig. 1 is a side elevational view of a furnace 50 equipped in accordance with the provisions of this invention.

Fig. 2 is a transverse sectional view through the adjustable balanced valve device appearing in Fig. 1.

Fig. 3 is a front elevational view of the parts New Brunswick, N. J.

1930. Serial No. 491,135

seen in Fig. 2, a part being broken away and shown in section for the disclosure of details, and Fig- 4 is a fragmentary detail sectional View upon the plane of line IV-IV of Fig. 3. I Referring to the drawing for describing in detail the structure therein illustrated, the reference character L indicates an ordinary furnace having the usual fire door 1 and ash, pit or air supplying door 2.

The reference character G indicates a chimney, and the reference character H indicates an ordinary length of pipe constituting the smoke flue extending between the furnace L and the chimney in the usual manner.

According to the present invention the flue H is preferably wide open throughout its entire length so that no mechanical part, such as the usual dampers or the like, are present for obstructing the free passage of gases and smoke between the furnace and the chimney, and this wide open flue or pipe is provided with an extension-pipe 3 projecting downwardly therefrom, the lower end of said extension-pipe 3 being turned laterally and carrying at its open end a balanced draft regulating valve device indicated generally by the reference character A. The extensionpipe 3 is in open communication at all times with the interior of the flue or pipe H so that air moving inwardly through thevalve A may pass'up wardly along the extension and into the pipe H,

as indicated by the arrow 4, to mingle with the smoke and gases moving along the pipe I-I, as in-; dicated by the arrow 5.

It will be understood that the amount of smoke and gases moving along the pipe H from the furnace is largely dependent upon the amount of draft, or pull, in the chimney. This draft may be supplied wholly through the furnace or partly through the furnace and partly through the ex tension 3, and it will accordingly be further understood that the amount of smoke and gases drawn from the furnace will be dependent upon the size of the passage-way through the extension 3. If the size of passage-way through extension 3 be reduced then the furnace will feel relatively more of the pull, or draft, of the chimney, while if the size of the passage-way through the extension be enlarged so that the pull of the chimney is sup-'- plied to greater degree by air through said extension then the furnace will feel a correspondingly less amount of pull from the chimney.

By making the extension pipe 3 to project in a direction downwardly to an appreciable extent below the main pipe or flue I-I places the lower open end of said extension in such relation to the pipe 1-1 that the light gases and smoke moving through the pipe H will not be likely to reach said open end and pass out into the furnace room or cellar. The light weight of the smoke and 5 gases naturally tends to keep them from downward movement through the extension.

The intimate metallic contact of the extension pipe with the main pipe H causes the extension pipe and its contents to become more or less heated so that the volume of air within the extension is always moving upwardly and is thus made to positively combat any downward movement of gases from the flue.

By making the lower end of the extension pipe to curve laterally a further impedance or bafiie is offered against likelihood of the smoke and gases at any time reaching the open end of the extension.

The laterally turned disposition of the lower end of the extension 3 also provides a desirable relationship of parts for the proper mounting and operation of the balanced valve device A, said valve being preferably arranged in a normally'vertical position as indicated.

It sometimes occurs, as just after placing a new supply of coal within a furnace that an ex- .cess volume of gases within the furnace becomes suddenly ignited and produces a light explosion within the furnace. If the smoke pipe connected with the furnace should be restricted by a cross damper or the like so that this gas can not move freely to the chimney then the gas is discharged in greater or less proportion outwardly through the furnace doors and into the cellar, this .being .a common form of annoyance where ordinary cross-dampers are used in smoke pipes.

According to the present invention however the. wide open condition of the smoke pipe H at all times provides for ample discharge of gases therethrough from the furnace and the draft regulating device herein illustrated at all times maintains a substantially constant draft condition within the furnace.

It may be here noted that the balanced valve A is so constructed as toclose automatically whenever a back pressure is felt downwardly through the extension 3, thus suitably preventing the escape of smoke and gas at any time downward- 15 through said extension.

- The balanced valve device A includes a light valve disc B of sheet metal'pivotally mounted within a stiff metallic carrying frame 6 which is firmly attached to the end edge portion of the laterally turned lower end part 7 of the extension 3. This frame is of general ring shape and provides an annular portion 8 which has a reduced inner end 9 telescoping snugly Within the end of the part 7.. The frame 6.is rigidly fixed to the part 7 by suitable means, .as by the prickpunch parts .10 illustrated so that the frame is immovable with respect to the extension 37 at all times.

Extending ornamental parts as 11 and 12 may be provided integral with the main ring shaped portion of the frame or not as may be desired.

The pivotal axis of the valve disc B is disposed .at one side of the centre of said disc, substantiallyxas indicated, so that the segmental portion as .13 which lies at one side of the pivotal axis is relatively larger than the segmental portion 14 which lies at the opposite side, and said axisti's disposed preferably in a diagonal position, also approximately as indicated, .so that the 7 segmental portion '13 is at the upper side of the pivotal axis and the segmental portion 14 is at the lower side of said pivotal axis.

In order that the segmental portion 14 may have equal or slightly greater weight than the portion 13 there is provided a weight element 15 connected with the portion 14 at a point removed from the pivotal axis. This weight element is preferably separately formed and detachable so that weight elements of different weight may be substituted. In the instance illustrated the weight element consists of inner and outer members 16 and 1'7 interiorly threaded and having thread engagement with a short screw member 18 which extends through a suitable aperture in the material of the segmental portions 14 and has its opposite ends engaging the members 16 and 17. p

The manner of pivotally mounting the valve disc within the frame 6 may take any desired form. Preferably however a cross rod as 20 is attached .at the rear surface of the disc for this purpose, as by means of rivets or the like as 21, the opposite ends of this cross rod being tapered down to provide cones 22-22 which fit within the suitably hollowed inner ends of a pair of adjustable screws '23-'23 one .at each side of the frame, said screws being held respectively, by lock nuts 24, against movement out of adjusted relationship with respect to the cone shaped ends of the cross rod 20.

At a point midway between the opposite cone shaped ends of the cross rod, and in the axial plane of said ends, the cross rod is provided with an aperture 25 mating an aperture 26 which is formed through the sheet metal material of the valve disc. Extending loosely through these mating apertures is a screw 27. A scale rod 28 which is arranged to project laterally from the outer surface of the valve disc is enlarged at its inner end to provide a nut-like portion 29 having its threaded socket 30 engaging the outer end of the screw 27. The inner end or portion of the screw 27 carries a nut 3-1 which presses against the inner surface of the cross rod 20, the

portions 29 and 31 thereby constituting a clamp engaging against the interposed portions of the valve disc and cross rod to hold the screw 27 and the scale rod rigidly, but readily detachably, connected with the valve disc.

The screw 27 is of suflicient length and Weight to substantially balance the weight of the scale rod, it being noted that the screw projects at one side of the pivotal axis of the valve disc, while the scale rod projects at the opposite side of said axis.

To detach the screw 2'? and the scale rod from the valve disc B it is simply necessary to unscrew the screw from the scale rod, and this is useful in that it permits not only the easy assembly and disassembly of parts but provides for the substitution of screws and scale rods of different weights relative to each other and to the remainder of the valve as may be required to meet the draft conditions in different installations.

Fitted upon the scale rod is a weight 32 which when this weight element 32 is at its innerthat there will be only a very light tendency for the disc to swing closed against the stop 34. With the weight 32 in its inner position only a very slight draft upwardly through the extension 3 will cause the disc to swing toward its open position against stop 35.

The stops 34 and 35 are carried upon the frame 6 in appropriate relation to the pivotal axis, the stop 34 being arranged to define the closed position of the valve disc and the stop 35 to define the extreme open position of said disc.

By adjusting the weight 32 to a relatively further distance outwardly along the scale rod, that is outwardly away from the pivotal axis, the efiiciency of said weight for moving the valve disc to closed position will be correspondingly increased.

It will be understood of course that the greater size of the segmental portion 13 of the valve disc, with respect to the segmental portion 14, renders said disc sensitive to the effort of air to pass said disc. The passing air, acting most strongly upon the larger segment will move said segment in the direction in which the air is moving. An inwardly moving draft will swing the disc open to a degree dependent upon the strength of the draft and the position of the weight 32 along the length of rod 28, while an outwardly moving draft will swing the disc closed against the stop 34, the latter movement being preferably assisted by at least some gravity tendency of the disc.

The furnace L as illustrated is equipped with a suitable power blower C, driven by motor 36, to force air through pipe 3'7 beneath and through the grate 38. A branch air pipe 39 extends from the blower into the combustion chamber above the grate, and manually adjustable valves 40 and 4 .1 are shown for regulating the exact amounts and proportion of air delivered above and below the grate by the blower.

The volume of air forced into the furnace beneath the grate, considered with the proportional volume delivered by the blower into the combustion chamber, is regulated so as to be in just sufficient quantity and proportions, one volume with respect to the other, to effect the proper burning of the coal upon the grate and the efiicient combustion of gases within the combustion chamber, all without the assistance of any so-called natural draft through the grate. The valves 40 and 41 are carefully set so as to produce just the desired balance as between the volume of air delivered beneath the grate and that delivered Within the combustion chamber, and eificient operation of the furnace requires that this balance shall not be upset.

The flue H and chimney G are of course necessary elements but it is intended that the extension 3-? and its control valve device, etc., as illustrated and as above described, shall be so co-related with the blower that the function of the flue and chimney shall be limited as nearly as possible to the carrying off of the spent and poisonous gases and smoke from the combustion chamber leaving the balance of air volumes in the furnace undisturbed and the process of combustion accurately under the control of the blower at all times.

To this end the valve device A is made highly sensitive to passing air drafts and is capable of being readily balanced to automatically admit air in varying ample volumes to insure that the draft pull of the chimney upon the furnace i will be only sufficient to safely carry off spent gases from the upper portion of the furnace. The entire mechanism as thus constructed and arranged provides for highly accurate, and at the same time easy and convenient, control of the fire and the economical consumption of fuel.

The entire apparatus, when once set, will operate automatically to attain this result. When the valves 40 and 41 have been once adjusted they will maintain a given balanced relationship between the air volumes delivered above and below the fire as long as the blower is in operation, and the extension 3 and its valve will provide for the constantly uniform and safe removal of spent gases without at any time disturbing the balance.

It is sometimes desirable to provide for an emergency escape of gases and air pressures from the furnace and flue, and to this end the presout invention proposes that the valve device A shall be so constructed as to automatically afford the desired relief whenever circumstances require it.

Instead of making the stop 34 as a relatively rigid element to positively define the closed position of the valve disc B, this stop is made as a yielding element, capable of limiting the closing movement of the valve disc under ordinary normal conditions, but at the same time being capable of permitting continued movement of the valve disc beyond the normal closed po-' sition of said disc and thereby enabling the upper portion of the disc to swing outwardly, and hence to what may be called a reverse open position, to any desired extent sufiicient to relieve the excessive pressure behind it. i

A suitable form of yieldable structure for the stop 34 is illustrated in the drawing as consisting of a light helical spring attached by its outer end to the inner surface of the metal frame 6, as by a rivet or other appropriate fastening device 42, the material of the spring extending inwardly from said frame and being curled around behind the lower portion of the valve disc approximately as indicated.

Under normal conditions this helical spring constitutes a stop in the appropriate position for defining the closed position of the valve disc, but whenever an excessive pressure is applied against the valve disc from within the flue the spring readily uncoils as the result of inward pressure from the segment I l, and thus automatically permits the valve disc to move into its reverse open position.

The spring will of course always maintain a resilient pressure against the segment 14 urging the disc to return to normal closed position as soon as the emergency has passed.

As many changes could be made in this construction without departing from the scope of the invention as defined in the following claims,

it is intended that all'matter contained in the above description or shown in the accompanying drawing, shall be interpreted as illustrative only and not in a limiting sense.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:--

1. In a valve device for smoke flues, where said valve device includes a valve disc pivotally mounted to swing into and out of closed position, counter weight means for said disc comprising a weight rod projecting laterally from one side of the disc, a weight projecting from the opposite side of the disc to counter balance the weight rod with respect to the pivotal axis of the disc,

said last mentioned weight having a portion extending loosely through an opening of the disc and into detachable connection with the adjacent end of the weight rod whereby said weight and said weight rod are detachably connected with the disc, and a weight adjustable along said weight rod toward and away from said pivotal axis of the disc.

2. In a valve device for smoke flues, where said valve device includes a valve disc pivotally mounted to swing into and out of closed position, counter weight means for said disc comprising a weight rod projecting laterally from one side of the disc, a weight projecting from the opposite side of the disc to counter balance the weight rod with respect to the pivotal axis of the disc, said last mentioned weight consisting of an elongated screw having one end portion projecting through an opening of the disc into threaded engagement with the adjacent end of the weight rod, a nut threaded adjustably upon said screw movable therealong to co-cperate with the adjacent end of the weight rod to clamp the weight rod into operative assembly against the disc, and a weight adjustable along said weight rod toward and away from said pivotal axis.

3. In a valve device for smoke fiues, where said valve device includes a valve disc pivctally mounted to swing into and out of closed position, counter weight means for said disc comprising a cross rod extending across the disc serving as a pivotal mounting means therefor, a weight rod projecting laterally from one side of the disc, a weight projecting from the opposite side of the disc to counter balance the weight rod with respect to the pivotal axis of the disc, said last mentioned weight consisting of an elongated screw having one end portion projecting through mating openings of the disc and cross rod and into threaded engagement with the adjacent end of the Weight rod, a nut threaded adiustably upon said screw movable therealong to clamp the disc and cross rod between itself and the adjacent end of the weight rod, and a weight adjustable along said weight rod toward and away from said pivotal axis of the disc.

4. A draft device for furnaces comprising in combination a smoke flue having an air opening thereinto, a valve for controlling said opening balanced to move from closed to open position in response to air drafts moving through said opening into the flue, and means serving to limit the closed position of said valve but yieldable under abnormal pressure from the valve to permit movement of the valve into a reverse open position.

5. A draft device for furnaces comprising in combination a smoke flue having an air opening thereinto, a weighted pivotally mounted valve in said opening operable by passing air drafts to regulate movement of air inwardly through said opening, and a stop to define the normal closed position of said valve, said stop consisting of a said opening and being intended for operation helical spring fixed by one end to the wall of the opening and having the remainder of its length coiled against said valve in a position to be uncoiled by movement of the valve.

6. A draft device for furnaces comprising in combination a smoke flue having an air opening thereinto, a valve for controlling said opening balanced to move from closed to open position in response to air drafts moving through said opening into the flue, and means serving to limit the closed position of said valve but yieldable under abnormal pressure from the valve to permit movement of the valve into a reverse open position, said limiting means consisting of a helical spring fixed by one end to the wall of the opening and having the remainder of its length coiled against said valve in a position tobe uncoiled by movement of the valve.

'7. A draft device for furnaces,-comprising, in combination with a smoke flue having an air opening thereinto, a valve normally closing said opening intended for operation by passing drafts, mounting means by which said valve is mounted for movement to one side of its closed position by a draft in one direction and for opening movement to the opposite side of its closed position by a draft in the opposite direction, and means to yieldingly restrict opening movement of the valve in one direction while not restricting opening movement of the valve in the opposite di rection.

S. A'draft device for furnaces comprising, in combination with a smoke flue having an air opening thereinto, a valve normally closing said opening intended for operation by passing drafts, mounting means by which said valve is mounted for opening movement to one side of its closed position by a draft in one direction and for opening movement to the opposite side of its closed position by a draft in the opposite direction, and 1 15 means to yieldingly restrict opening movement of the valve in one direction said means engagr 9. As an article of manufacture, a draft regulating device for furnaces, comprising a frame having an opening therethrough, a valve pivotally mounted within the frame normally closing and the frame to yieldingly restrict opening movementof the valve in one direction said step being resilient and adapted thereby to urge return of the valve to closed position.

THORNTON W. PRICE. 

